Targeted analysis of protein termini

Area of Science:

• Proteomics
• Molecular Biology
• Biochemistry

Background:

• Protein termini (N- and C-termini) are crucial for protein function and regulation.
• Current methods often rely on database annotations, potentially missing novel or unpredicted protein forms.
• In vivo acetylation is a common post-translational modification affecting protein function.

Purpose of the Study:

• To develop and validate a method for targeted analysis of in vivo acetylated protein N- and C-termini.
• To identify previously unannotated protein termini.
• To investigate novel post-translational modifications like N-terminal propionylation.

Main Methods:

• Selective enrichment of in vivo acetylated protein N- and C-termini.
• Mass spectrometry-based identification without chemical derivatization.
• Iterative database search strategy accounting for enrichment protocols.

Main Results:

• Identification of 263 annotated and 87 unpredicted N-acetylated N-termini.
• Identification of 168 annotated and 193 unpredicted C-termini.
• First report of in vivo N-terminal propionylation.

Conclusions:

• The study identified a substantial number of novel protein termini, suggesting extensive unannotated transcription or processing.
• The developed method enhances protein and gene annotation accuracy.
• Findings highlight the importance of exploring beyond routine database searches for comprehensive proteome understanding.